Average Liquid Film Thickness of Annular Air-Water Two-Phase Flow in 8x8 Rod Bundle


In order to develop detailed model of the annular two-phase flow the average liquid film thickness is an important parameter. It can significantly affect the occurrence of dryout and post-dryout phenomenon on heater surfaces. Most research on film thickness has been focused on pipe flows. Data in rod bundle geometry are very limited. However data in rod bundle geometry is much more valuable for reactor safety modeling and calculations. Because of this, an experiment to measure liquid film thickness has been performed for the air-water annular flow in a 8 x 8 BWR rod bundle. Film thickness data were obtained both on the rods and on the channel wall. Data were recorded at four axial locations within the rod bundle. This included locations just before and just after a spacer grid. This allowed the spacer grids effect on the film thickness to be evaluated. The minimum film thickness was on the center rod. Also, the presence of the spacer grid resulted in reduced film thickness.


Nuclear Engineering and Radiation Science

Research Center/Lab(s)

Center for High Performance Computing Research

Keywords and Phrases

Air; Boiling water reactors; Film thickness; Liquid films; Air-water two phase flows; Annular flows; Annular two-phase flow; Axial locations; Detailed modeling; Reactor safety; Rod bundles; Wall-films; Two phase flow; Rod film thickness; Wall film thickness

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version


File Type





© 2018 Elsevier, All rights reserved.

Publication Date

01 Oct 2018